1. Field of the Art
The present invention relates to television circuits and, more particularly, to a partitioning scheme for a television receiver for providing the video and signal processing circuits on a single large scale integrated circuit.
2. Description of the Prior Art
Since the first television receiver was built comprising discrete circuitry and vacuum tubes television receivers have evolved to the present wherein the television receiver comprises a plurality of integrated circuits in combination with the tuner and high powered portions of the circuit as well as the cathode ray tube (CRT) utilized to provide the television picture.
Generally, contemporary television receivers include a radio frequency (RF) tuner which is coupled to a tuned input of an intermediate frequency (IF) stage the output of which is coupled to both a video processing stage and a signal processing stage wherein the video composite TV signal is processed to drive the cathode ray tube with the output of the signal processing stage being utilized to drive the horizontal and vertical deflection yokes of the television cathode ray tube so that the video information supplied from the video processor is converted to a recognizable picture on the CRT.
Typically, contemporary television receivers require a minimum of four integrated circuits to provide the functions of a basic black and white television receiver. For example, the television receiver can be partitioned in a manner wherein four integrated circuits may be utilized to provide (1) video IF amplifier and video detection (2) video signal processing (3) horizontal sync information processing and (4) vertical sync information processing.
The aforedescribed combination of multiple integrated circuits results in a problem that is related to all such television receivers which is caused by undesirous signal radiation that occurs to a greater or lesser extent because of the use of external coils in tuned circuits required for detection of the composite TV stereo operating in a high signal environment. For instance, this radiation usually emanates from a portion of the television receiver where the IF signal levels are at the highest: usually at the interface of the video detector stage of the television receiver where the external tuned circuits are utilized for video detection. Another problem with television receivers utilizing multiple integrated circuits is that exact DC signal bias levels must be maintained between each one of the multiple integrated circuits. It is quite difficult to achieve these bias levels and an attempt to so requires external biasing circuitry to be utilized. Still further, the use of multiple integrated circuits can be relatively expensive when compared to a television receiver that required only a single large scale integrated chip to provide the aforementioned functions.
Hence, the present invention is concerned with combining the basic functions of a television receiver, i.e., the IF amplifier/detector stage, video processing and signal processing circuits into a single large scale integrated circuit having optimum partitioning. Such a single integrated circuit can eliminate radiation problems as aforedescribed with elimination of tuned circuits by the use thereof as well as save costs by eliminating the need for multiple integrated circuits.